It is well known to provide conveyors that space articles, or in addition provide accumulation of articles in a conveyor system where a plurality of individual zones for separating articles are provided. The standard in the industry for such conveyors utilizes powered rollers to provide the conveying surface for the articles. One known arrangement is for the rollers to be idlers, with each group of idlers being driven by individual drive belts that engage the underside of the rollers. One approach of this type of spacing/accumulating conveyor system is the Hardwick U.S. Pat. No. 4,264,004.
While this type of conveyor system has proven to be successful, one major shortcoming is that the movement of articles is subjected to considerable vibration due to the bottom of the article bumping across the individual rollers during the conveying movement. Especially where the rollers are relatively widely spaced in order to help control the costs of such conveyors, many articles are subjected to considerable distortion or damage. This is especially prevalent with respect to electronic products or other packages with delicate contents. Also, damage due to distortion of the underside of certain articles as each of the rollers is engaged and bumped during conveying, such as occurs with paperboard drink can carriers, is intolerable and a different approach is clearly needed. Another example of this type of prior art conveyor system is illustrated in the Garrity U.S. Pat. No. 5,060,785.
In some article conveyor systems, such as for transferring and storing of luggage and baggage in airline terminals and the like, there has been some useful development in the use of conveyor belts, rather than powered rollers, as set forth in the Malavenda U.S. Pat. No. 4,227,607. Since this type of article is understood by the public to include rough handling, these systems have not been refined with a view to handling articles that are subject to distortion or damage. Thus, for example, these conveyor systems in most instances do not depart from the usual approach of allowing the articles to bump and vibrate during the conveying operation. Furthermore, the cost of such systems is exaggerated due to the need to employ individual motors for each of the sections or zones in the conveyor system.
A more recent approach than is represented by the '607patent is illustrated in the patent to Saar, U.S. Pat. No. 4,361,225. In this arrangement, a relatively narrow driven belt is powered by a circular 0-ring drive belt that must be shifted laterally so as to be fully tensioned around a drive roll for a narrow belt. In the neutral position, the 0-ring belt is laterally shifted and positioned so as not to be tensioned, and thus to eliminate the driving function. The nature of the 0-ring drive belt and the relative narrow width of the belt in the '225 patent seriously limits the use of a conveyor system constructed in accordance with this disclosure.
With the above analysis in mind, what is missing in the art is broadly defined as a spacing conveyor system, and more specifically in accordance with the preferred embodiment, a multiple zone accumulation conveyor system that overcomes these problems. The need that exists is for a conveyor system for spacing/accumulation especially adapted for articles that must be protected from jarring during handling and which makes use of a simplified drive mechanism. In the preferred embodiment, a particular advantage is sought for a conveyor system having a drive mechanism employing a single drive belt to power the plurality of belt conveyors making up a spacing and/or accumulation conveyor system. As an adjunct to this improved arrangement, the system is to be simplified and reduced in cost substantially over the prior art arrangements.